Typhoon Nepartak has hit eastern Taiwan, driving thousands of people from their homes, disrupting power supply and forcing the cancellation of more than 500 flights.

The storm was packing sustained winds of 240 kilometres per hour, and gusts at up to 296kph as it rumbled towards the eastern counties of Hualien and Taitung.

The "super-typhoon" is expected to dump torrential rain on the whole island with mountainous areas forecast to be deluged with up to 600 millimetres, potentially triggering landslides that have in the past claimed hundreds of lives.

Two death and 66 injuries were reported, while bullet train services have been suspended.

All fishing boats have been called back to port as waves — as high as 14 metres, according to TV reports — battered the eastern coast.

Nepartak leaped from tropical storm to the category-five equivalent of a tropical cyclone on Tuesday, and has been intensifying since.

Since Tuesday, more than 3,000 visitors have been evacuated from Green Island and Orchid Island, two popular tourist spots off south-eastern Taitung County, local government officials said.

Taiwan's Defence Ministry said more than 35,000 soldiers were on standby to help with evacuations and disaster relief, while 90 shelters had been set up.

More than 300 international and 254 domestic flights have been cancelled, an emergency services website showed, while schools and offices have also been ordered to shut.

Conditions are expected to deteriorate significantly before the storm hits, the weather bureau said.